As known in the art, entry of alphanumeric characters on devices equipped with a standard twelve (12) key mobile device keypad typically involves either pressing multiple keys (chording) or tapping (actuating) a key multiple times (multi-tap) to select, or compose, a given alphanumeric character. Those skilled will appreciate that for the multi-tap method, a short delay (referred to hereinafter as a “composition timeout”) is provided during within which if the same key is pressed, the alphanumeric character displayed is replaced by the next character. The composition timeout is typically fairly short, on the order of one second, for example. Failure to enter a tap on the same key during the composition timeout leads to the currently displayed character being seized by the device and fixed on the display.
In many applications involving the entry of sensitive data such as passwords, the input field is masked or otherwise concealed during input such that the actual input remains invisible, effectively proscribing another's ability to read sensitive data from the input field. In a traditional environment where a complete keyboard is provided, this type of concealment is generally adequate and poses little problem (although, as will be seen below, this also has drawbacks). In a system using the multi-tap method, however, where a certain amount of visual feedback is required to ensure that the correct character is keyed, complete concealment of the character in question proves problematic and typically leads to many false entries, especially when the user's attention during entry is not sufficiently focused on the task at hand. This can prove particularly inefficient when entering passwords as many systems refuse access after a small number of incorrect entries to prevent password discovery by a brute force, trial and error approach.
One example prior art method for concealing characters and even entire input fields during multi-tap entry is as follows. As characters are composed, they are made visible to the user in clear text. For example, in order to compose the character “c” the user taps key number 2 thrice, first revealing the character “a” followed by “b” and arriving at “c” on the third tap. Once the wished for character has been composed and seized by the device, the character displayed is concealed, or masked, by replacing it with a wildcard character such as, for example, an asterisk. Once the character has been concealed in this fashion however, there is generally no way that the user can view it again. Additionally, and as will be understood by a person of skill in the art, as further characters are entered and concealed in this fashion, there is generally no way that the user can view any (or all) of these characters (as they are masked, again typically with an asterisk).
Additionally, due to the variety of input modes that exist on many mobile handsets (for example lowercase mode, uppercase mode, symbol mode, numeric mode, title case mode, etc. which can be switched between by, for instance, user interaction with a selection list generated by soft Key selection) users frequently enter unexpected or unwanted characters because they think the device is in one particular mode, when in fact, the device is in a different mode. For example, in title case mode where the first letter in a string is capitalized, the user may easily enter “Password” instead of “password” without noticing it. As passwords are typically case-sensitive this can lead to a proliferation of password entry errors. This drawback can be further compounded when the indicator of the mode currently active while the user is entering masked data is not clearly displayed. For example, the current mode indicator (assuming it is visible at all) may be located away from the input field and outside of the user's area of attention (positioned at a corner of the screen, for example).
Similar drawbacks also arise in more conventional devices which include full keyboards (e.g. a QWERTY keyboard) combined with a single-tap entry method As discussed above, in these cases the character being entered is completely invisible and is typically replaced immediately with an asterisk. Due to the low quality of some keypads as well as their small size, especially on handheld devices, the probability that a wrong key is depressed, two keys depressed at once or the same key depressed twice can be quite high (meaning that instances with respect to which there will be an incorrect sequence entry will occur at an undesirable frequency). Additionally, features such as initial letter capitalization (or “title mode”) can be defaulted to on even for some full keyboard devices.